This invention relates to fittings for plastic insulated electric cables in general and more particularly to the mechanical design of prefabricated fittings or fitting parts with an elastic insulator and metallic housing.
For plastic insulated medium and high voltage cables, especially for those with insulation of thermoplastic or cross-linked polyethylene, fittings and fitting parts have recently been developed which are pushed onto a suitably prepared cable end or are plugged into appropriately prepared cable ends. These fittings and fitting parts consist substantially of an elastic insulator made of an ethylene-propylene terpolymer rubber or silicone rubber which is provided with elements for controlling the electric field. The fitting has an internal hole which is smaller than the outside diameter of the respective, prepared cable conductor. The fitting part, when pushed onto the cable conductor, or when a cable end is plugged into a fitting part, is elastically expanded sufficiently that a press fit without voids is obtained on the conductor insulation. The press fit at the same time provides a seal against moisture. In order to make such fittings and fitting parts otherwise safe against accidental contact, or in order to permit a metallic connection of the cable shields through the fitting, provision has also been made to surround the elastic insulators with a tubular metallic housing.